Manipulator having motorized grasper and method



Oct. 3, 1967 c. E. SAUNDERS, JR 3,344,936

MANIPULATOR HAVING MOTORIZED GRASPER AND METHOD Fi'led Oct. 19, 1964 5 Sheets-Sheet l INVENTOR.

CHARLES E. SAUNDERS, JR.

ATTQRNEY.

Oct. 3, 1967 c. E. SAUNDERS, JR 3,344,936

MANIPULATOR HAVING MOTORIZED GRASPER AND METHOD Filed Oct. 19, 1964 3 Sheets-Sheet 2 INVENTOR 22 CHARLES E. SAUNDERS,JR.

aw/m ATTORNEY.

Oct. 3, 1967 c. E. SAUNDERS, JR 3,344,936

MANIPULATOR HAVING MOTORIZED GRASPER AND METHOD Filed Oct. 19, 1964 3 Sheets- Sheet 5 FIG. 3

FIG. 4

POWER GRIP INVENTOR. CHARLES E. SAU NDERS,JR.

Qw /M ATTORNEY.

United States Patent 3,344,936 MANIPULATOR HAVING MOTORIZED GRASPER AND METHOD Charles E. Saunders, Jr., Springdale, C0nn., assignor to American Machine & Foundry Company, a corporation of New Jersey Filed Oct. 19, 1964, Ser. No. 404,810

a 5 Claims. (Cl. 214-1) This invention relates to mechanical manipulators and more specifically to mechanisms for the remote operation of a slave gripping device or tongs to cause the gripping device to simulate to a greater or lesser degree the operation of a master hand or handle spaced from the slave. In use, for example, devices of this kind may be situated in a chamber containing radioactive substances in which case the master control would be outside the chamber at a convenient position. The slave gripping device may be in the form of two fingers but of course a more elaborate form of grasping mechanism may be used. For simplicity the word tongs is used to indicate any of a variety of such forms of grasping mechanisms. The master handle or grip may also take various forms and will be referred to as the handle or alternately as the actuator. The master control handle is adapted to move the slave tongs bodily so that the latter may be brought into proximity with an object to be grasped, the handle then being actuated to cause the slave tongs to close upon the subject.

The improvement, comprising the present invention, relates 'to manipulators of the kind described in the Goertz et al. U.S. Patent 2,764,301 and in particular, by reference to FIG. 36 of that patent, the present invention is concerned with an improvement with respect to the function performed by tape 175 relating to the opening and closing of the handle 62 and grasper 63 of that patent.

In order to allow a wide range of movement, manipulators of the kind represented by the Goertz et al. patent frequently include a master portion pivotally suspended from a through-tube adapted to pass through the screening Wall of a chamber containing substances from which shielding is desired such to pass through the screening Wall of a chamber containing substances from which shielding is desired such as radioactive toxic or explosive materials in which case the through-tube, with its associated linkages, both supports the master and slave portions andalso causes the slave portion to move in accordance with the controlling movements of the master portion and its associated mechanisms. To be completely flexible in use the handle must be'capable of movement in three directions, commonly termed the X, Y and Z movements. X motion is that from side to side parallel to the screening wall, Y motion is movement towards or away from the wall, while the Z motion is movement vertically up and down. To permit such Z motion the master portion maybe adapted to extend telescopically and the slave portion will besimilarly arranged so as to move in sympathy with the master portion. In such manipulators provision ismade to preserve balance during any movements, whether of the two portions together under the direct manual effort of the operator, or of the slave portion with respect to he master portion, by a source of power under the control of the operator.

In such a manipulator if the slave tongs simulate or follow the movement of the manually operated control handle, with the force on the tongs being derived from the manually applied force, a degree of delicacy or accuracy or touch may be obtained, whereas, if the slave is oper-- ated-by a force from a different source, even though this may be hand controlled, some sensitivity or touch is in danger of being lost. Usually, the master handle and slave tongs are maintained normally in an open position by means of springs. This arrangement has the disadvantage in that the operating force on the slave is less than the applied force by that amount required to overcome the force exerted by the springs. This could to some extent be overcome by providing some means for introducing a mechanical advantage, but this usually requires the sacrifice of some extent of movement of the slave tongs thereby reducing their sensitivity. Furthermore, to give the tongs versatility, they are usually connected with the master handle through a flexible band guided over pulleys or the like. The position of the band will often be tortuous and thus losses will occur in the transmission of force to the tongs.

In accordance with the present invention an alternative force under the control of the operator is provided to supplement or to be used in lieu of the manual force applied by the operator at the handle to cause a gripping action at the tongs. This alternative feature is provided by a power source mounted upon the manipulator and connected to the linking means which coordinates movement of the handle and tongs and in a manner that does not interfere with the normal functioning of the manipulator.

It is accordingly a principal object of the invention to provide an improvement to manipulators of the kind shown in the Goertz et al. US. Patent 2,764,301 in which a force manually applied at the handle and conveyed by a flexible tape to tongs is adapted to be supplemented or to be optionally replaced by an alternative force under the control of the operator. This alternative force being provided by a power source suitably mounted on the manipulator such as that section of the telescopic master portion directly supported by the through tube and connected to the flexible tape at a point on the telescopically movable section of the master portion by a suitable coupling. Alternatively for example the power source may be mounted on the horizontal member.

It is a further object of the invention to provide an arrangement wherein the slave tongs are operated from a master handle by means of a link which is provided with a means for coupling or connecting thereto a source of power for supplementing or replacing the manually applied force.

Still a further object of the invention resides in providing a manipulator in which a power source is introduced automatically when the hand grip is producing greater than a predetermined pressure. This permits the tongs to be moved or directed with great ease and delicacy until a desired object is grasped by the tongs whereupon the power source, set to provide a predetermined force, enables a firm grip on the object to be effected and maintained. The pressure on the handle at which the power grip is introduced may be adjustable and means may be provided for altering the magnitude of the power grip applied to the slave tongs so as to suit the weight etc. of the object being handled by the tongs. As a further feature, means may be provided so that on releasing the grip on the master handle, the power grip is automatically removed when said grip has been reduced below a predetermined magnitude.

Additional objects, advantages and novel features will become apparent from the description and drawing in which:

FIG. 1 shows a typical installation of the relevant por- FIG. 3 is an illustration showing the tong tape sche matic.

FIG. 4 shows the taping system for an alternate embodiment.

As used herein the term power grip refers to the force applied to the slave grasper or tongs from the non-manual source provided by the invention.

Referring to FIG. 1 of the drawing, a manipulator comprising a horizontal member 6, a master arm 7 and a slave arm 8 comprising the three main assemblies of the manipulator, are shown mounted in a shielding or safety wall 10 shown in phantom and containing a window 10a. The supporting through-tube 11 of horizontal member 6 is adapted to be fitted in an aperture through the safety wall and carries at one end the upper section 12 of the master arm 7 and at the other end the slave arm assembly 13. The lower section 12a of the master arm 7 is mounted so as to be retractable between the parallel tubes of the upper section 12 in a telescoping manner. The handle 14 is pivotally mounted at the lower end of the master arm assembly 12a and the tongs 15 are pivotally mounted at the end of the slave arm assembly 13. The manipulator assembly includes counter-balancing means to afford ease of movement in any direction; such counterbalancing weight arrangements are well known and form no part of the present invention.

FIG. 2 shows a preferred embodiment of the present invention, in which the handle 14 is coupled to the tongs 15 in FIG. 1 by a high tensile steel tape 16 passing over a plurality of free-running pulleys 17. The gripping members of the tongs are spring loaded to the open position, and the tape 16 is connected taut between the handle and tongs, i.e. Without any slack, the pulleys 17 being positioned to allow the tape to run freely and moving with movable portions of the manipulator in such a manner that the tape length is maintained in its taut condition. In this arrangement movement of tape 16 (see FIG. 3) is in the direction of arrow 16a effecting only a closure of the tongs. The tape 16 is connected to the handle 14 and tongs 15 in such a way that any pressure by the operator to cause the fingers of the handle to move together causes the tape to be displaced and so pulls the fingers of the tongs together in a gripping function. It will be apparent that the tape may be only partially displaced depending on the size of the object grasped. The tape path and pulley positions are shown in simplified form in FIG. 3. The power grip of the present invention is supplied by a piston 18 or like actuator motor which has a stroke of suitable distance to close the tongs and apply tension to the tape and is capable of an appropriate force e.g. 40l00 lb. thrust, may be used. The operating piston of the actuator 18 is attached to a short strip of steel tape 19 which is in turn attached to the tape 16 by clamp 25 which interconnects the handle 14 and grasper I15 in the manner described in detail in Goertz et al. US. Patent 2,764,301. When the actuator is operated the piston moves from left to right pulling the flexible connector 19 which is connected to the flexible tape 16 thereby closing the fingers and applying a gripping force. The motor or actuator 18 is connected to a pressure source 20 via a solenoid-operated valve 21 as is shown in FIG. 2. This solenoid valve is connected to a suitable electrical supply via a control switch 22 (FIG. 1) within reach of an operator using the manipulator. In this way, the actuator can be switched on to cause a gripping by the tongs. It is apparent that the power grip is available for use in lieu of the manual means or in addition thereto.

Any suitable commercially available motor pneumatic, hydraulic or electric may be used in lieu of the pneumatic arrangement shown in the preferred embodiment.

In some cases, it may be desirable to vary the grip force available, for example, when delicate objects have to be held for a length of time such that the operator might suffer discomfort and in such case a pressure regulating valve 23 is installed in the pneumatic supply line. This valve can be pre-adjusted to give the required grip, and provision of this feature eliminates the necessity for use of a ratchet in the handle since the operation of the actuator will maintain a desired grip even when the handle is released. The actuator 18, tape 16 and clamps 24 and 25 must be so positioned that they do not restrict spatial movements or telescopic action of the master portion nor interfere with the operation of the device. In accordance with the invention this has been achieved in the practical embodiment shown by positioning the actuator centrally at the upper end of the telescopic portion of the master arm in which position it has minor effect upon the balancing during Z motion.

In a modification, the handle 14 and switch 22 may be arranged so that only when more than a predetermined manual pressure is being exerted will the power grip be applied automatically. Further the arrangement may be such that the power grip will then continue to be applied until the hand pressure is reduced to below said predetermined pressure or below a different predetermined pressure.

In FIG. 2a details of the clamp 25 are illustrated. The clamp is attached to the end of the flexible piece 19 which is secured at the other end by a connector 24 attached to the piston rod 18a. As shown the clamp 25 secures the piece 19 to metal tape 16 which corresponds to metal tape 175 in the above-referred to Goertz et al. Patent 2,764,301. The structure of the clamp is not critical and comprises two protector plates 26 and 27 with ends flanged outward positioned in a housing 28 having an opening 29 through which the metal tapes 16 and 19 may be introduced. Screw 30 (FIG. 2a) secures the assembly by pressing the plates 26 and 27, through which tapes 16 and 19 pass, against the lower portion of housing 28.

An alternative arrangement for applying the force from the actuator is shown in FIG. 4. This embodiment employs an actuator 18 to move a pulley 45 positioned to engage the tape 16 at a position between two of the free-running fixed center pulleys 46 and 47. In this arrangement, the actuator will force the tape from its normal path and so exert a pull at the tongs to cause a gripping action. Pulleys and 108 (FIG. 3 as well as FIG. 4) correspond functionally to similarly referenced pulleys in US. Patent 2,764,301 (see FIG. 36 of that patent.)

It will be apparent that in a modification of the invention the handle control may be arranged so that only when more than a predetermined manual pressure is being exerted will the power grip be applied. This may be accomplished by use of a conventional tension actuated switch or other tension responsive mechanism. It may also be arranged so that the power grip will continue to be applied until the hand pressure is reduced to below said predetermined pressure or below a different predetermined pressure. Moreover, it will be apparent that the power grip element may be mounted at various convenient locations on the manipulator.

It will be apparent that various alternate arrangements of detail may be made without departing from the inventive concept as set forth in the accompanying claims.

I claim:

1. In a remote control manipulator comprising a horizontal support and a master arm and slave arm pivotally connected at opposite ends of said support and including a grasper at the free end of said slave arm, a manual actuator at the free end of said master arm and mechanical linking means for coordinating movement between said grasper and said actuator, the improvement comprising a motorized means mounted on said manipulator and arranged, through the action of said motor, to move said linking means and operate said grasper.

2. The improvement of claim 1 wherein said motorized means is mounted on the master arm.

3. The improvement of claim 1 wherein said motorized means comprises a pneumatic motor.

4. The improvement of claim 1 wherein said motorized means comprises a pneumatic motor mounted on said master arm and the piston of said motor is connected by means of a clamp to said mechanical linking means.

5. In the method of manipulating a remote control manipulator comprising a horizontal support and a master arm and slave arm pivotally connected at opposite ends of said support and including a grasper at the free end of said slave arm, a manual actuator at the free end of said master arm by means of mechanical linking tapes which coordinate movement between said grasper and said actuator, improvement comprising motorizing the movement of the grasper on the slave arm by means of a motor attached to said linking means and upon demand operating said grasper by initiating a power source connected to said motor.

References Cited FOREIGN PATENTS 9/1964 France. 12/1964 Great Britain. 

1. IN A REMOTE CONTROL MANIPULATOR COMPRISING A HORIZONTAL SUPPORT AND A MASTER ARM AND SLAVE ARM PIVOTALLY CONNECTED AT OPPOSITE ENDS OF SAID SUPPORT AND INCLUDING A GRASPER AT THE FREE END OF SAID SLAVE ARM, A MANUAL ACTUATOR AT THE FREE END OF SAID MASTER ARM AND MECHANICAL LINKING MEANS FOR COORDINATING MOVEMENT BETWEEN SAID GRASPER AND SAID ACTATOR, THE IMPROVEMENT 